Thyroxine (T4) is the main hormone your thyroid makes. Your thyroid hormones are important because they control how your body uses energy from the food you eat. (Photo Credit: iStock/Getty Images) T4 ...

Thyroxine (T4) levels differ from person to person but usually exist within a consistent range. Abnormal T4 levels can lead to various symptoms and complications, including mental health and digestive ...